Quick: Need advice on heat range under egg

Hi, I build a home made incubator and just started a batch last night. The temp was pre-stabilized and the humidity is 55% currently. Although I have one of those cheap temp sensors for indoor outdoor temps. It reads 100 on the unit and about 98.8-90.1 on the probe that is under one of the eggs furthest from the light. I also have a stove temp sensor that is in the incubator leading to the display on the outside. I use that just to double check the other and it's reading 101 degrees.

Does the low temp under the egg sound ok or should I bring the temp up a little to get at 99.5 under the egg? I figure it's only been 24 hours. Once the eggs start development then heat will rise under the egg?

If you have no fan or the fan is not moving air around enough then you will see colder air at the top than at the bottom because of thermal layering. http://cmfarm.us/stillair.html
If thats not the issue then it may be that some of your thermometers are off a little bit. Ether way your incubator is well within safe hatching range.

I have a 12V .2A computer fan blowing over the light circulating the air. I might use a larger slower fan as this one is pretty noisy, I have a few 120MM PSU fans some place.

Anyway, your thinking I should just leave it be? as I have a pretty consistent 100 degree temp going. It has been reading 101 on the oven temp without fluctuation. I would just rather keep the temp higher then lower i suppose.

haha sorry, kinda just going on and on, this is my first batch as you can tell. 24 eggs!

ohh also, if I check and find infertile eggs, can I toss in others in place of the infertile ones or will they freak out with the timing? having off set batches in one batch?